.KOA

Introduction

Koala Painter was the drawing program sold with the KoalaPad, a graphics tablet from Koala Technologies. Its Commodore 64 picture files became the standard way to store a C64 multicolour bitmap, and most C64 paint programs and converters still read and write them.

A picture is 160 × 200 wide pixels in up to 16 colours, with the C64’s limit of four colours in each 4 × 8 cell. On the C64 disk the files have names starting with a special character and PIC; copied to a PC they usually get the extension .koa or .kla.

Structure

A Koala file is a copy of the memory the C64’s video chip reads, saved as a normal program file. It is 10003 bytes long. The first two bytes are the load address, usually $6000 (00 60, low byte first). Then come 8000 bytes of bitmap, 1000 bytes of screen memory, which hold two of each cell’s colours, 1000 bytes of colour memory for the third, and one byte for the background colour shared by the whole picture.

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